Backpack



FIG. 1 is a perspective view of a backpack showing my new design, the curved line segments at the strap ends throughout the views being understood as the boundary of the design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 front elevational view thereof;

FIG. 5 bottom plan view thereof;

FIG. 6 is a left side elevational view thereof; and,

FIG. 7 is a rear elevational view thereof.

The broken lines shown on the surface of the article throughout the views are understood to represent stitching. 

The ornamental design for a backpack, as shown and described. 